Reciprocating Saw Blade Having Variable-Height Teeth and Related Method

ABSTRACT

A reciprocating saw blade, for use in a portable power reciprocating saw including a chuck for releasably engaging the saw blade, includes a tang having an elongated axis and being engageable with the chuck for attaching the saw blade to the reciprocating saw. The saw further includes a blade portion having a cutting edge that defines a plurality of cutting teeth. The cutting teeth define a repeating pattern of successive groups of teeth. Each group of teeth is less than about a half inch in length, and includes a plurality of laterally offset teeth, at least one relatively high first tooth and at least one relatively low second tooth. Prior to tooth set, the at least one relatively high first tooth is at least about 0.002 inch higher than the at least one relatively low second tooth.

CROSS-REFERENCE TO PRIORITY APPLICATION

This patent application is a continuation of U.S. patent applicationSer. No. 11/963,474, filed Dec. 21, 2007, now U.S. Pat. No. 8,210,081,which claims priority to U.S. Provisional Patent Application No.60/934,262, filed Jun. 12, 2007, entitled “Reciprocating Saw BladeHaving Variable-Height Teeth And Related Method”, both of which arehereby incorporated by reference in their entireties as part of thepresent disclosure.

FIELD OF THE INVENTION

The present invention relates to saw blades, and more particularly, toreciprocating saw blades including recurring patterns of high and lowteeth and related methods.

BACKGROUND

A reciprocating saw machine is a hand-held power saw that includes achuck for releasably engaging the saw blade and driving the saw blade ina reciprocating motion through a work piece. The reciprocating motioncan be an orbital cutting action, a straight or linear cutting action,or an angled cutting action. Reciprocating saws are sometimes referredto as recip saws, or jig saws, and reciprocating saw blades likewise aresometimes referred to as recip blades or jig saw blades. Reciprocatingsaws are typically driven by electric motors (e.g., cord or cordlesssaws), or are pneumatically driven. Well known reciprocating saws aresold under the brand names “Sawzall™” by Milwaukee Electric ToolCorporation and “Tiger Saw™” by Porter-Cable Corporation.

A typical reciprocating saw blade includes a blade portion having acutting edge defined by a plurality of teeth axially spaced relative toeach other along one side of the blade, and a non-working edge formed onan opposite side of the blade relative to the cutting edge. A tang forreleasably connecting the blade to the chuck of a reciprocating sawextends from an inner end of the blade. Typical reciprocating saw bladessuffer from the need for a trade-off between maximizing wear resistanceand maximizing durability. Harder blade materials tend to be more wearresistant, whereas softer blade materials tend to be more durable.Durability is associated with teeth that are robust, resistant tofracture and/or exhibit an ability to withstand impact.

The teeth of a reciprocating saw blade typically include a cutting tip,a rake face formed on one side of the tip, and a clearance surfaceextending from the tip and formed on an opposite side of the tiprelative to the rake face. The rake face forms a rake angle relative toan axis perpendicular to a reference plane, which may be defined by theplane extending between the tips of successive teeth havingsubstantially the same height, such as successive unset teeth. Theclearance surface forms a clearance angle relative to the referenceplane.

One way to affect the cutting performance of a reciprocating saw bladeis to modify the clearance angle of the cutting teeth. For example,increasing the clearance angle may allow the teeth to cut faster.However, teeth with greater clearance angles may be more delicate andthus more likely subject to breakage than teeth with shallower clearanceangles.

The need to restrict the clearance angle is especially acute forreciprocating blades, because the reciprocating cutting pattern is veryabusive to blade teeth. In contrast to other types of blades such asband saw blades that continuously move in one direction during cutting,reciprocating blades oscillate back and forth through a work piece in anorbital, linear and/or angular cutting action, and thus createsubstantial forces on all sides of the teeth.

In addition, because a reciprocating blade must accelerate from zero tomaximum speed and back again to zero during each stroke, the blade is atoptimal cutting speed during only a portion of the forward stroke,typically less than about 50% of the forward stroke. Furthermore, thelength of each stroke is very short, i.e., typically about ¾ inch toabout 1¼ inches. As a result, reciprocating saw blades have relativelyshort repeating tooth patterns of about ½ inch or less to maximize thenumber of repeat patterns of teeth.

Prior art band saw blades have employed high-low teeth and varyingclearance angles. For example, some band saw blades have recurringpatterns of groups of teeth wherein each group includes teeth withrelatively high tips and teeth with relatively low tips. Band saw bladesalso have employed teeth with varying clearance angles. Conventionalwisdom generally has taught away from applying high-low teeth and/orteeth with relatively steep clearance angles (e.g., about 35° orgreater) to reciprocating saw blades. As indicated above, in starkcontrast to band saws, for example, reciprocating saws are hand-heldpower saws that subject the recip blades to an abusive reciprocatingcutting action. Thus, not only are the rake faces subject to substantialcutting forces, but the clearance surfaces formed on the back sides ofthe teeth likewise are subject to substantial cutting forces on thereturn strokes. Recip blades are particularly susceptible to failurefrom tooth fracture or chipping. Accordingly, it has been believed thatif high-low teeth were applied to a recip blade, the relatively highteeth would be overly exposed and subjected to excessive cutting forces,and thus more likely subject to fracture or chipping. Similarly, it hasbeen believed that if relatively steep clearance angles were applied torecip teeth (e.g., about 35° or greater) any teeth with such narrowincluded angles would be too delicate to withstand the relativelyabusive reciprocating cutting action and associated cutting forces, andtherefore would be subject to premature fracture or chipping.Accordingly, the performance of prior art recip blades, such as cuttinglife and/or durability, have not always been at levels desired.

It is an object of the present invention to overcome one or more of theabove-described drawbacks and/or disadvantages of the prior art.

SUMMARY OF THE INVENTION

In accordance with a first aspect, the present invention is directed toa reciprocating saw blade for use in a portable power reciprocating sawincluding a chuck for releasably engaging the saw blade. Thereciprocating saw blade comprises a tang having an elongated axis andengageable with the chuck of the reciprocating saw for attaching the sawblade to the reciprocating saw. A blade portion has a cutting edgedefined by a plurality of cutting teeth. The cutting teeth define arepeating pattern of successive groups of teeth, each group of teeth isless than about a half inch in length, includes a plurality of setteeth, at least one relatively high tooth, and at least one relativelylow tooth. Prior to tooth set the at least one relatively high tooth isat least about 0.002 inch higher than the at least one relatively lowtooth. In some embodiments of the present invention, the difference inheight prior to tooth set between the at least one relatively high toothand the at least one relatively low tooth is within the range of about0.003 inch to about 0.006 inch, and in some such embodiments is withinthe range of about 0.0035 inch to about 0.005 inch.

In currently preferred embodiments of the present invention, therelatively high teeth define at least one first clearance angle, and therelatively low teeth define at least one second clearance angle that isgreater than the first clearance angle. Preferably, the first clearanceangle is less than or equal to about 35°, and the second clearance angleis greater than about 35°. In some embodiments, the first clearanceangle is within the range of about 25° to about 35°, and the secondclearance angle is within the range of about 35° to about 45°.

In some embodiments of the present invention, each group of teethincludes at least one unset leading tooth, and a plurality of settrailing teeth. In some such embodiments, the at least one unset leadingtooth is a relatively high tooth, and at least one of the plurality ofset trailing teeth is a relatively low tooth. In some such embodiments,at least one of the set trailing teeth is a relatively high tooth. Insome embodiments, a plurality of the set trailing teeth define differentset magnitudes relative to each other. In some such embodiments, theplurality of set trailing teeth includes at least one first set toothdefining a relatively heavy set magnitude, and at least one second settooth defining a relatively light set magnitude. In some suchembodiments, the at least one first set tooth defining a heavy setmagnitude is a relatively low tooth, and the at least one second settooth defining a relatively light set magnitude is higher than the heavyset tooth. In some such embodiments, the at least one relatively lowheavy set tooth defines a steeper clearance angle in comparison to theat least one relatively high light set tooth.

In some embodiments of the present invention, each group of teethincludes unset teeth between first and second pluralities of set teeth.In some such embodiments, each of the first and second pluralities ofset teeth includes at least one relatively high set tooth, and at leastone relatively low set tooth. In some such embodiments, the unset teethdefine at least one first clearance angle, the set teeth define at leastone second clearance angle, and the at least one first clearance angleis less than the at least one second clearance angle.

The reciprocating saw causes the reciprocating saw blades of the presentinvention to move in a reciprocating motion between a rear most positionand a forward most position. The reciprocating motion defines an axis ofmotion extending between i) a first position of a reference point of thesaw blade when the saw blade is in the rear most position, and ii) asecond position of the reference point when the saw blade is in theforward most position. The cutting edge of the recip saw defines anapproximate cutting line extending between the tips of successive teethhaving substantially the same height. In accordance with another aspectof the present invention, the cutting line is oriented at an acute angleof greater than about 3° relative to the axis of motion. In some suchembodiments, the acute angle is within the range of about 4½° to about6°. In some embodiments, the tang defines an elongated axis oriented atan acute tang angle relative to the cutting line, and the acute tangangle at least contributes to orienting the cutting line at an acuteangle of greater than about 3° relative to the axis of motion.

In some embodiments of the present invention, each group of teethincludes at least one first relatively high unset tooth, a firstplurality of set teeth following the first relatively high unset toothand set to one side of the blade portion, at least one second relativelyhigh unset tooth following the first plurality of set teeth, and asecond plurality of set teeth following the at least one secondrelatively high unset tooth and set to an opposite side of the bladeportion relative to the first plurality of set teeth. In some suchembodiments, a plurality of at least one of the first and secondpluralities of set teeth define different set magnitudes and differentheights relative to each other. In some such embodiments, at least oneof the first and second pluralities of set teeth includes at least oneintermediate height tooth that is relatively light set, and at least onelow tooth that is relatively heavy set. The intermediate height toothdefines a height between the heights of the relatively high and lowteeth, and the difference in height between each intermediate heighttooth and adjacent high and low teeth prior to tooth set is at leastabout 0.002 inch.

In some embodiments of the present invention, each group of teethdefines a variable pitch pattern, including at least one relativelycoarse pitch and at least one relatively fine pitch. In some suchembodiments, each group of teeth includes an unset raker tooth defininga relatively coarse pitch.

In accordance with another aspect, the present invention is directed toa method comprising the following steps:

Mounting within the chuck of a reciprocating saw a reciprocating sawblade including a tang having an elongated axis and a blade portionhaving a cutting edge defined by a plurality of cutting teeth. Thecutting teeth define a repeating pattern of successive groups of teeth,each group of teeth is less than about a half inch in length, andincludes a plurality of teeth of different species, including aplurality of set teeth, at least one relatively high tooth, and at leastone relatively low tooth. Prior to tooth set the at least one relativelyhigh tooth is at least about 0.002 inch higher than the at least onerelatively low tooth;

Driving the reciprocating saw blade with the reciprocating saw in areciprocating cutting action between forward and backward strokes; and

Cutting the work piece by engaging the work piece with thereciprocatingly driven reciprocating saw blade and, in turn, during eachof a plurality of forward strokes, engaging multiple teeth of the samespecies with the work piece, bearing a relatively higher chip load withthe relatively high teeth in comparison to the relatively low teeth,protecting the relatively low teeth from chipping or damage with thepreceding relatively high teeth, and cutting the work piece with therelatively low teeth at a higher speed in comparison to the relativelyhigh teeth.

The driving step comprises driving the reciprocating saw blade in areciprocating motion between a rear most position and a forward mostposition. The reciprocating motion defines an axis of motion extendingbetween i) a first position of a reference point of the saw blade whenthe saw blade is in the rear most position, and ii) a second position ofthe reference point when the saw blade is in the forward most position.The cutting edge defines an approximate cutting line extending betweenthe tips of successive teeth having substantially the same height. Inaccordance with another aspect of the present invention, the methodfurther comprises the step of positioning or orienting the cutting lineat an acute angle of greater than about 3° relative to the axis ofmotion. In some such embodiments, the step of positioning or orientingthe cutting line at an acute angle includes: (i) providing the tang sothat the elongated axis of the tang defines an acute angle relative tothe cutting line, and/or (ii) mounting the tang within the chuck so thatthe cutting line is oriented at an acute angle relative to the axis ofmotion.

One advantage of the reciprocating saw blades of the present inventionis that the height differential between cutting teeth can providesignificantly improved performance, such as improved cutting speedand/or durability, in comparison to prior art recip blades. Accordingly,the reciprocating saw blades of the present invention are capable ofwithstanding higher cutting forces, providing increased chip production,and improved cutting speeds in comparison to prior art reciprocating sawblades.

Other advantages of the currently preferred embodiments of the presentinvention include the provision of sturdy, wear-resistant cutting edgesthat better withstand higher cutting forces and enable increased cuttingspeeds. The high teeth with relatively shallow clearance angles aresturdier than the low teeth with relatively steep clearance angles, andthereby protect the less sturdy lower teeth. Thus, because the lowerteeth are protected, they can possess much steeper clearance angles thanthose of typical reciprocating saw blades, and thus can cut faster andwith less feed force. Accordingly, a significant advantage of the toothpatterns of the currently preferred embodiments of the present inventionis that the relatively steep clearance angles facilitate enhancedcutting speed while the teeth with shallower clearance angles facilitateenhanced durability. Accordingly, the reciprocating saw blades of thepresent invention are capable of providing significantly improved bladelife, and cutting performance throughout the blade life, in comparisonto conventional reciprocating saw blades.

Yet another advantage of some currently preferred embodiments of thepresent invention is that the acute cutting angle formed between theplane defined by the cutting edge and the plane defined by thereciprocating motion of the saw can further enhance cutting speedwithout materially impacting the durability of the blade. In someembodiments, this acute angle is at least partially a result of the tangextending at an acute angle relative to the cutting edge (e.g., a lineextending between the tips of successive unset teeth or teeth of thesame height). The steeper the cutting angle, the greater is the heightdifferential between the high and low teeth, and thus the effect oncutting performance provided by such height differential. Yet anotheradvantage is that the acute cutting angle formed between the cuttingedge plane and the plane defined by the reciprocating motion of the sawdoes not increase the load on the clearance surfaces of the teeth on thereturn stroke of the blade, thereby further enhancing performancewithout reducing durability.

Other objects and advantages of the present invention and/or embodimentsthereof will become readily apparent in view of the following detaileddescription of currently preferred embodiments and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side elevational view of an embodiment of a repeating toothpattern of a reciprocating saw blade;

FIG. 1B is a top plan view of the repeating tooth pattern of FIG. 1A;

FIG. 2A is a side elevational view of another embodiment of a repeatingtooth pattern of a reciprocating saw blade;

FIG. 2B is a top plan view of the repeating tooth pattern of FIG. 2A;

FIG. 3A is a side elevational view of another embodiment of a repeatingtooth pattern of a reciprocating saw blade;

FIG. 3B is a top plan view of another embodiment of the repeating toothpattern of FIG. 3A;

FIG. 4 is a side elevational view of another embodiment of a repeatingtooth pattern of a reciprocating saw blade;

FIG. 5 is a side elevational view of another embodiment of a repeatingtooth pattern of a reciprocating saw blade;

FIG. 6 is a partial, side elevational view of a reciprocating saw blademounted within a chuck of a reciprocating saw;

FIG. 7 is a table showing test results of an embodiment of thereciprocating saw blade of the present invention as compared to a priorart reciprocating saw blade;

FIG. 8 is a table showing test results of embodiments of thereciprocating saw blade of the present invention as compared to priorart reciprocating saw blades;

FIG. 9 is a side elevational view of another embodiment of areciprocating saw blade having a variable tooth height and/or setforming a wavy pattern;

FIG. 10 is a side elevational view of another embodiment of areciprocating saw blade having another variable tooth height and/or setforming a wavy pattern;

FIG. 11 is a side elevational view of another embodiment of areciprocating saw blade having another variable tooth height and/or setforming a wavy pattern;

FIG. 12 is a side elevational view of another embodiment of areciprocating saw blade having unset raker teeth alternately followed byeither plural left set or plural right set trailing teeth;

FIG. 13 is a side elevational view of another embodiment of areciprocating saw blade defining a variable pitch pattern;

FIG. 14 is a side elevational view of another embodiment of areciprocating saw blade defining another variable pitch pattern; and

FIG. 15 is a partial, side elevational view of another embodiment of areciprocating saw blade defining a variable height, clearance and setmagnitude.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In FIGS. 1A and 1B, a first embodiment of a reciprocating saw blade ofthe present invention is indicated generally by the reference numeral100. The saw blade 100 is used in a reciprocating saw. A reciprocatingsaw is a portable power saw that is typically hand-held and includes achuck for releasably engaging the saw blade and driving the saw blade ina reciprocating motion. Reciprocating saws are sometimes referred to asrecip saws or jig saws and these terms are used synonymously herein.Reciprocating saws are typically driven by an electric motor (cord orcordless), or are pneumatically driven. Reciprocating saws are driven inany of a variety of cutting actions, including orbital, linear and/orangled. Reciprocating saw blades are blades that include at least onetang for mounting the blade within the chuck of a reciprocating saw.Reciprocating saw blades are sometimes referred to as recip blades orjig saw blades and these terms are used synonymously herein.

The recip saw blade 100 comprises a plurality of recurrent or repetitivepatterns of teeth, i.e., tooth patterns 105, that have variable heightsand clearance angles. As shown in FIG. 1B, the saw blade 100 defines alongitudinal axis “LA”, and a transverse axis “TA” that extends betweenthe sides of the saw blade 100. Preferably, the transverse axis TA isnormal to the sides of the saw blade 100 and/or the longitudinal axisLA.

As shown typically in FIGS. 1A and 1B, each tooth pattern includes aplurality of teeth having at least one high tooth and at least one lowtooth. The teeth having a greater height may be referred to as “highteeth”, and the teeth having a lower height may be referred to as “lowteeth”. In the present embodiment, the high teeth in each group have agreater height and a shallower, i.e., smaller, clearance angle than dothe lower teeth in the group.

In the embodiment shown in FIGS. 1A and 1B, the repeating tooth pattern105 is a three-tooth pattern that includes an unset leading, or rakertooth 110, a first trailing set tooth 115R, and a second trailing settooth 115L. As shown in FIG. 1B, the trailing teeth 115R and 115L areset laterally to opposite sides of the blade relative to each other.Thus, the sides of the set teeth 115R and 115L form an oblique anglerelative to a respective side of the blade 100, and an outer corner ofeach of the set teeth extends laterally from the respective side of theblade. As can be seen in FIG. 1B, when viewed from the cutting directionof the saw blade, the set tooth 115L is set to the left of the blade 100and thus is referred to as a “left set” tooth, and the set tooth 115R isset to the right of the blade 100 and thus is referred to as a “rightset” tooth. As used herein, the designation “L” refers to a left-settooth, and the designation “R” refers to a right-set tooth.

As shown in FIG. 1A, the unset tooth 110 defines a first height 130, andthe set teeth 115L and 115R define a second height 135. As can be seen,the height 130 of the unset tooth is greater than the height 135 of theset teeth, and the height differential between the set and unset teethis referred to as ΔH. The height of each tooth in this and otherembodiments of the present invention described herein is measured as thedistance between a tip (e.g., the tip 145) of the respective tooth and aselected reference plane of the blade 100 located below the tip. In FIG.1A, the cutting edge 112 is represented by a line extending between thetips 145 of the successive unset teeth 110, and a reference plane thatis parallel to the back edge of the blade (not shown) is indicated bythe broken line 140. Accordingly, in the illustrated embodiment, theheights 130, 135 of the teeth are measured as the distance between therespective tip and the reference plane 140. However, as may berecognized by those of ordinary skill in the pertinent art based on theteachings herein, the tooth heights may be measured relative to the backedge or any other reference plane located below the tips of the teeth.In addition, in this embodiment, and the other embodiments of theinvention described herein, the heights of the set teeth are measuredprior to tooth set. Although the heights of the set teeth may bemeasured after the teeth are set, and thus the height differentialbetween high and low teeth may be determined after the teeth are set, itis typically easier to measure and/or determine the heights and heightdifferentials prior to the teeth being set.

In the illustrated embodiment, the difference in height ΔH prior totooth set between the height 130 of the high unset teeth and the height135 of the low set teeth is at least about 0.002 inch, is preferablywithin the range of about 0.003 inch to about 0.006 inch, and mostpreferably is within the range of about 0.0035 inch to about 0.005 inch.Note that although the figures herein show the height differential ΔH asthe difference between the heights of the set and unset teeth, themeasurements provided herein are the ΔH measurements prior to, and notafter tooth set. Although in the current embodiment the set teeth 115L,115R have the same height, they may alternatively define any combinationof height differentials, provided that each of the heights of the setteeth 115L, 115R is lower than the height 130 of the respective unsetteeth of the same group. The height differential ΔH between the high andlow teeth may be varied depending upon a variety of factors, such as thetype of material to be cut, the materials of construction of the sawblade, and the desired cutting performance, such as the desired cuttingspeed and/or the desired blade life. Accordingly, the tooth heights andheight differentials described herein are only exemplary and can bechanged as desired, or otherwise as deemed necessary to meet therequirements of a particular application.

Each of the teeth in tooth pattern 105 defines a rake surface 180, andat least one clearance surface 185 extending from the tip 145 andlocated on an opposite side of the tip relative to the rake surface 180.As shown in FIG. 1A, each clearance surface 185 defines a clearanceangle 190 relative to a reference plane, such as the cutting edge 112.In the illustrated embodiment, the relatively high unset tooth 110defines a smaller clearance angle than that of the lower set teeth 115R,115L.

As shown in FIG. 1A, each high unset tooth 110 includes a primaryclearance surface defining a first primary clearance angle “A”, and eachlow set tooth 115L, 115R includes a primary clearance surface defining asecond primary clearance angle “B”. Each tooth 110, 115 also includes asecondary clearance surface that extends between the respective firstclearance surface defining the clearance angle A or B and the gullet.Each secondary clearance surface defines a secondary clearance angle“C”. In the illustrated embodiments of the present invention, the firstclearance angle A of the high unset teeth is preferably less than about35°, more preferably is within the range of about 25° to about 35°, andmost preferably is within the range of about 28° to about 33°. In theembodiment of FIGS. 1A and 1B, the first clearance angle A is about 30°.Also in the illustrated embodiments of the present invention, the secondclearance angle B is preferably greater than about 35°, more preferablyis within the range of about 35° to about 45°, and most preferably iswithin the of about 38° to about 43°. In the embodiment of FIGS. 1A and1B, the second clearance angle B of the low set teeth is about 40°. Thethird clearance angle C is preferably greater than the respective firstor second primary clearance angles A or B, and in the illustratedembodiments is about 45°. In some embodiments of the present invention,the third clearance angle C for the relatively low teeth is greater thanthe third clearance angle C for the relatively high teeth. Althoughthese clearance angles and ranges are described with reference to theembodiment of FIGS. 1A and 1B, they equally may be applied to the otherembodiments of the present invention disclosed herein. In addition, asmay be recognized by those of ordinary skill in the pertinent art basedon the teachings herein, the specific height differentials and clearanceangles described herein are only exemplary, and numerous other heightdifferentials, clearances angles, and combinations thereof equally maybe employed depending upon any of numerous different factors, such asthe material to be cut, the desired cutting speed, and/or the desiredwear life of the blades. In addition, if desired, the high and low teethmay have the same clearance angle, the higher teeth may have variableclearance angles, and/or the lower teeth may have variable clearanceangles.

FIGS. 2A and 2B show a blade 200 having a four-tooth repeating pattern205. The features of the recip blade 200 are similar to the recip blade100 with the exception of the features described below, and thereforelike reference numerals preceded by the numeral “2” instead of thenumeral “1” are used to indicate like elements.

As shown in FIGS. 2A and 2B, both the high and low teeth may be set, andthe teeth may be set to varying degrees. The four-tooth pattern 205includes two pairs of set teeth, each pair having different setmagnitudes. A first pair of high set teeth 220R, 220L has a first height230 measured with respect to the reference plane 240, and a second pairof low set teeth 215R, 215L has a second lower height 235 measured withrespect to the reference plane 240. As can be seen, the first height 230of the teeth 220R, 220L is greater than second height 235 of the teeth215R, 215L. The high set teeth 220R, 220L are set to a first setmagnitude, and the low set teeth 215R, 215L are set to a secondmagnitude that is greater than the first set magnitude of the highteeth. Thus, the corners of the low set teeth 215R, 215L extendlaterally farther than do the corners of the respective high set teeth220R, 220L. In addition, the low set teeth 215R, 215L define a steepersecond clearance angle B than the first clearance angle A of the higherset teeth 220R, 220L. In the illustrated embodiment, the low set teeth215R, 215L each have a relatively steep second clearance angle B ofabout 40°, and the high set teeth 220R, 220L each have a relativelyshallow first clearance angle A of about 30°. As can be seen, in thisembodiment, the high set teeth 220R, 220L are located between respectivelow set teeth 215R, 215L, and vice versa, so that they form pairs ofsuccessive teeth set in the same direction. As shown in FIG. 2B, thefirst successive pair of teeth 215R, 220R is set to the right, and thesecond successive pair of teeth 215L, 220L is set to the left. Oneadvantage of this and other embodiments of the present invention is thatthe low set teeth 215L, 215R provide relatively steep, aggressivecutting surfaces to facilitate faster cutting seeds, while therelatively high set teeth 220L, 220R protect the respective low teeth215L, 215R to facilitate improved blade life.

FIGS. 3A and 3B show a blade 300 that is similar to the blade 200, withthe addition of an unset raker tooth. The features of blade 300 aresimilar to the blade 200 with the exception of the features describedbelow, and therefore like reference numerals preceded by the numeral “3”instead of the numeral “2” are used to indicate like elements. The blade300 defines a five-tooth pattern 305 that includes an unset raker tooth310 having a first height 330, a first pair of high set teeth 320R and320L also having a first height 330, and a second pair of low set teeth315R and 315L having a second height 335. As can be seen, the unsetraker tooth 310 is followed by a low right set tooth 315R, a high rightset tooth 320R, a low left set tooth 315R and a high left set tooth320L. As can be seen, tooth height is measured relative to the referenceplane 340. As with the other embodiments illustrated herein, althoughall of the high teeth are shown as having the same height 330, theseteeth exhibit the same tooth height prior to tooth set; however, aftertooth set the outer corners of the high set teeth are slightly lowerthan the outer corners of the high unset teeth. The term “outer corner”is used herein to mean the corner of the respective tooth laterallyspaced furthest from the centerline of the blade. The first height 330of the high teeth is greater than the second height 335 of the lowteeth. As shown in FIG. 3B, high set teeth 320R and 320L are set to afirst set magnitude, and the low set teeth 315R and 315L are set to asecond magnitude that is greater than the first set magnitude.

In the illustrated embodiment, the high unset raker tooth 310, and theset teeth 320R, 320L, each define a first clearance angle A that isrelatively small or shallow as compared to the second clearance angle Bof the low set teeth 315R, 315L. Alternatively, if desired, the high setteeth 320R, 320L may also define a relatively steep second clearanceangle B that is the same as or different from the second clearance angleB of the low set teeth 315R, 315L. In one example, the low set teeth315R, 315L define a second clearance angle B of about 40°, and the highunset raker tooth 310 and high set teeth 320R, 320L define a relativelyshallow first clearance angle A of about 30°.

FIG. 4 shows a blade 400 having a six-tooth pattern 405 that includespairs of set teeth with unset raker teeth located between the pairs ofset teeth. Otherwise, the features of the recip blade 400 are similar tothe recip blade 300 with the exception of the features described below,and therefore like reference numerals preceded by the numeral “4”instead of the numeral “3” are used to indicate like elements.

The six-tooth pattern 405 includes two unset raker teeth 410 having afirst height 430, two high set teeth 420R and 420L also having a firstheight 430 prior to tooth set, and two low set teeth 415R and 415Lhaving a second height 435 prior to tooth set. In the illustratedembodiment, the tooth height is measured relative to the reference plane440. The first height 430 of the unset raker teeth 410 and high setteeth 420R, 420L is greater than second height 435 of the low set teeth415R, 415L. The high set teeth 420R, 420L are set to a first setmagnitude, and the low set teeth 415R, 415L are set to a second setmagnitude that is greater than the first set magnitude. Accordingly, thetooth pattern of this embodiment is defined by a high unset raker tooth410, followed by a high, light left set tooth 420L, a low, heavy rightset tooth 415R, a high unset raker tooth 410, a low, heavy left settooth 415L, and a high, light right set tooth 420R. In this embodiment,the unset raker teeth 410 each define a first clearance angle A that isrelatively small compared to the second clearance angle B of both thehigh and low set teeth. In the illustrated embodiment, the high setteeth 420R, 420L define substantially the same clearance angle B as thelow set teeth 415R, 415L. In one example, the low set teeth 415R, 415Land the high set teeth 420R, 420L each define a second clearance angleof about 40°, and high unset raker teeth 410 each define a firstclearance angle of about 30°. However, as may be recognized by those ofordinary skill in the pertinent art based on the teachings herein, theseclearance angles are only exemplary, and numerous other clearance anglesmay be employed. For example, the relatively high set teeth 420R, 420Lmay define clearance angles that are more shallow than the clearanceangles B of the low set teeth 415R, 415L, or may define the sameclearance angle as the unset raker teeth 410.

FIG. 5 shows a blade 500 having a six-tooth pattern 505 that includes apair of unset raker teeth, followed by a first pair of right set teethdefining different heights and set magnitudes relative to each other,and a second pair of left set teeth defining different heights and setmagnitudes relative to each other. Otherwise, the features of the blade500 are similar to the blade 300 with the exception of the featuresdescribed below, and therefore like reference numerals preceded by thenumeral “5” instead of the numeral “3” are used to indicate likeelements.

The six-tooth pattern 505 includes two unset raker teeth 510 having afirst height 530, two first high set teeth 520R and 520L also having afirst height 530 prior to tooth set, and two second low set teeth 515Rand 515L having a second height 535 prior to tooth set. In the currentembodiment, height is measured relative to the reference plane 540. Thefirst height 530 of the unset raker and high set teeth is greater thansecond height 535 of the low set teeth. As can be seen, the two highunset raker teeth 510 are followed by the pair of right set teeth 515R,520R, which are in turn followed by the pair of left set teeth 515L,520L. The high set teeth 520R, 520L are set to a first set magnitude,and the low set teeth 515R, 515L are set to a second magnitude greaterthan the first set magnitude (i.e., the low teeth are “heavy set” andthe high teeth are “light set”). In this embodiment, the unset rakerteeth 510 each define a first clearance angle A that is relatively smallcompared to the second clearance angle B of the set teeth 515R, 520R,515L, 520L. In one example, the low set teeth 515R, 515L and the highset teeth 520R, 520L each define a second clearance angle B of about40°, and the high unset raker teeth 510 each define a first clearanceangle B of about 30°. However, as may be recognized by those of ordinaryskill in the pertinent art based on the teachings herein, any ofnumerous other clearance angles equally may be employed. For example,the high set teeth may define more shallow clearance angles than the lowset teeth, or may define substantially the same clearance angles as theraker teeth.

If desired, the reciprocating saw blades may be designed such that theunset teeth are the low teeth defining relatively steep clearanceangles, and the set teeth are the high teeth defining relatively shallowclearance angles. Thus, the variable heights and clearance angles may bereversed in comparison to that shown above. In addition, if desired, thehigh and low teeth may define substantially the same clearance angles.In addition, although the low teeth described above are shown as havingsubstantially the same height, the heights among the low teeth may vary(while remaining lower than the high teeth). Similarly, in toothpatterns having multiple high teeth, the high teeth all may havesubstantially the same height, or the heights may vary among the highteeth.

In the embodiments shown in FIGS. 1A and 3A-5, the unset tooth or teethhave substantially the same rake angle as the set teeth. The term “rakeangle” refers to the angle of the tooth face relative to a lineperpendicular to the reference plane, such as the reference planeparallel to the back edge of the blade described above, anotherreference plane extending between the tips of successive unset teeth orother successive teeth having substantially the same height as eachother, and/or an axis of motion defined by the reciprocating motion ofthe reciprocating saw. The rake angle is positive when the tooth anglesforwardly with respect to the forward direction of the reciprocatingcutting action, and negative when the tooth angles rearwardly withrespect to the forward direction of the reciprocating cutting action. Asshown in FIG. 1A, the forward or cutting direction of the recip blade isindicated by the arrow 182. In other embodiments, the unset tooth orteeth may have a rake angle that is different than the rake angles ofthe set teeth. In the illustrated embodiments, all of the teeth have arake angle that is about zero degrees. However, if desired, the lowteeth may be provided with positive rake angles (i.e., such that thebase of the rake face is rearward of the tip), or may be provided withmore positive rake angles than the high teeth, to further facilitateachieving faster cutting speeds.

In those embodiments showing multiple pairs of set teeth, e.g., FIGS.2A-5, a variable set magnitude is shown. Alternatively, if desired, thepairs of set teeth may all have the same or substantially the same setmagnitude.

Each tooth in the above-described tooth patterns defines a respectivetooth spacing measured between the tips of adjacent teeth, or ifdesired, measured between any of numerous other corresponding pointsbetween adjacent teeth. The tooth spacing is the inverse of the toothpitch (i.e., 1/pitch). Thus, for example, an “18 pitch” tooth spacing is1/18 or about 0.055 inch point to point between adjacent teeth. In thepreviously described embodiments, the tooth spacing is substantiallyconstant throughout the tooth patterns. However, the tooth spacing mayvary between teeth, and/or may vary according to a predetermined patternamong the teeth of the tooth pattern. Each tooth pattern also defines arespective number of teeth per inch (“TPI”). The currently preferredembodiments of the present invention fall within the range of about 6TPI to about 24 TPI, and include without limitation 6, 8, 10, 14, 18 and24 TPI. As an example of the relationship between TPI and pitch, 6 TPIcorresponds to 0.166 pitch (i.e., ⅙), 18 TPI corresponds to 0.056 pitch,and 24 TPI corresponds to 0.041 pitch.

Turning to FIG. 6, another reciprocating saw blade is indicatedgenerally the reference numeral 600. The recip blade 600 issubstantially similar to the recip blades described above, and thereforelike reference numerals preceded by the numeral “6” or preceded by thenumeral “6” instead of another lead numeral, are used to indicate likeelements. The reciprocating saw blade 600 includes an elongated bladeportion 650 having a repeating tooth pattern 605 opposite a back edge655. A tang 660 extends from an inner end of the blade portion 650 toallow the blade 600 to be releasably engaged with a chuck 675 or otherclamping device of a reciprocating saw. As indicated by the arrow inFIG. 6, the reciprocating saw causes the saw blade 600 to move in areciprocating motion defined by a forward stroke to the right in thefigure, and a rearward stroke to the left in the figure. During eachstroke, the recip blade 600 moves between a rear most position to theleft in the figure and a forward most position to the right in thefigure. The chuck 675 engages the tang 660 in manner known to those ofordinary skill in the pertinent art to releasably secure the recip bladeto the reciprocating saw. The chuck 675 may take the form of any ofnumerous chucks or other clamping mechanisms of reciprocating saws thatare currently known, or that later become known, and may include, forexample, a retaining collar 680 that receives the tang to secure thetang to the reciprocating saw. The tang 660 may have one or more tangapertures 690, and the collar 680 may have one or more collar apertures685 to allow a connecting element such as a stud or a pin to be insertedtherethrough to secure the recip blade to the saw.

As shown in FIG. 6, the recip blade 600 defines an acute cutting angle672 formed between (i) a cutting line defined by the teeth of the recipblade 600, such as a line extending between the tips of consecutiveunset teeth of the same height, and (ii) an axis, i.e., an axis ofmotion, shown for example as an axis “M” in FIG. 6, defined by thereciprocating motion of the recip blade 600. The axis of motion Mextends between i) a first position of a reference point of the sawblade when the saw blade is in the rear most position to the left in thefigure, and ii) a second position of the reference point when the sawblade is in the forward most position to the right in the figure. Thereference point may be any point located on the saw blade 600.

In the current embodiment, the tang 660 is positioned at an acute anglerelative to the blade portion 650, so that an elongated axis of the tang660 defines an acute tang angle 665 relative to the cutting line definedby the cutting edge 670. As shown in FIG. 6, the tang angle 665 issubstantially equal to the cutting angle 672 formed between the cuttingline and the axis of motion M. However, in other embodiments, thecutting angle 672 may be different than the tang angle 665. For example,the tang angle 665 may be smaller than the cutting angle 672, and thetang 660 may be mounted in the chuck 675 at an acute angle relative tothe axis M of the reciprocating motion to achieve a desired cuttingangle 672. Thus, the desired cutting angle 672 may be achieved solely byproviding a desired tang angle 665, by an angular mounting of the blade600 on the reciprocating saw, or by a combination of the tang angle 665with an angular mounting of the blade 600 on the reciprocating saw.

The cutting angle 672 is preferably greater than about 3°. As a generalmatter, the greater the cutting angle 672, the greater is the effect ofthe increased cutting angle on the height differential ΔH of thehigh-low teeth, and thus the greater is the effect on the cutting actionof the saw blade. As the cutting angle 672 is increased, it effectivelyincreases the height differential ΔH of the high-low teeth, and thuscauses the high teeth to take larger bites out of the work piece thanthey otherwise would with a lower cutting angle. Yet another advantageof a relatively steep cutting angle is that it may reduce the impact onthe clearance surfaces of the teeth during the return stroke. Arelatively steep cutting angle is about 4½° or greater. Reciprocatingsaw blades of the present invention embodying a relatively steep cuttingangle preferably define cutting angles within the range of about 4½° toabout 6°, and include as exemplary cutting angles 4½°, 5°, 5½° and 6°.However, as may be recognized by those of ordinary skill in thepertinent art based on the teachings herein, the reciprocating sawblades of the present invention may define any of numerous differentcutting angles and/or tang angles that are currently known, or thatlater become known, and may define no cutting angle at all, or aconventional cutting angle (about 3° or less).

In the currently preferred embodiments of the present invention, therepeating tooth patterns include between about 3 and about 10 teeth.Also, the length of each repeating pattern or group of teeth in thecutting direction of the saw blade is preferably less than or equal toabout ½ inch. Preferably, the length of the repeat pattern facilitatesat least two teeth of like species cutting a work piece during arespective stroke of the reciprocating saw, and the relatively shortrepeat patterns (about a ½ inch or less) facilitate this goal. As may berecognized by those of ordinary skill in the pertinent art based on theteachings herein, the repeating tooth patterns may include a differentnumber of teeth, or define a different length, depending upon the typeof saw blade and/or the application(s) of the blade. The reciprocatingsaw blades may include more than one repeating pattern, or additionalteeth may be located between or among the groups of teeth of therepeating pattern. In some embodiments of the present invention, thetooth patterns are as coarse as feasible for the material to be cut.Preferably, there are at least about 2 to 3 adjacent teeth engaging thework piece at any given time, and most preferably, multiple teeth of thesame species engage the work piece during a cutting stroke in order todistribute the cutting loads across the teeth. Accordingly, it may notbe desirable to employ relatively long repeat patterns where the teethof like species are relatively far apart because this will tend toprevent enough teeth of like species engaging the work piece during thesame cutting stroke.

One advantage of the tooth patterns of the present invention is thatthey provide a sturdy, wear-resistant cutting edge with increasedcutting efficiency and consequently increased cutting speeds. In theabove-described embodiments of the present invention, the high teethwith relatively shallow clearance angles are sturdier than the low teethand protect the low teeth, which have steeper clearance angles. The highteeth bear a higher chip load and protect the low teeth. Also, the lowteeth have corners set within or substantially within the profilescreated by the preceding high teeth of like set direction to protectagainst chipping or damage to the corners of the low teeth.

In some embodiments of the present invention, because the set teeth arelower than the unset leading tooth (or teeth), the corners of the setteeth are either not exposed, or are only slightly exposed outside ofthe profiles of the preceding unset leading tooth (or teeth). Therefore,the weaker, faster cutting set trailing teeth are substantiallyprotected by the unset leading teeth, thus facilitating increasedcutting speeds and/or durability in comparison to prior art recipblades. Thus, the offset trailing teeth may define steeper clearanceangles, and if desired, positive rake angles to facilitate a fasterspeed of cut without reducing the durability of the blade. Furthermore,for those embodiments having set teeth with varying set magnitudes, thisconfiguration not only provides protection to the set teeth, but alsoincreases the cutting power by increasing the cutting surfaces providedby the set teeth.

Thus, because the low teeth are protected, they can possess much steeperclearance angles than those of typical reciprocating saw blades, and canthus cut faster with greater efficiency and with less feed force.Accordingly, the teeth with relatively steep clearance angles facilitaterelatively fast cutting speeds, while the high teeth with relativelyshallow clearance angles facilitate blade durability. Therefore, therecip blades described herein can provide significantly improved bladelife, and cutting performance throughout the blade life, in comparisonto prior art recip saw blades.

FIG. 7 illustrates test results of an embodiment of a reciprocating sawblade of the present invention compared to a typical reciprocating sawblade. This embodiment, labeled “Chip Model”, has a tooth pattern with ahigh unset lead raker tooth and low trailing set teeth. The unset leadraker tooth has a clearance angle of about 30°, the trailing set teetheach have a clearance angle of about 40°, and the unset lead raker toothis about 0.004 inch higher than the trailing set teeth prior to toothset. This tooth pattern was tested against a typical reciprocating sawblade, labeled “R&D Control”, that does not have the height differentialor clearance angle features of the “Chip Model” blade.

In FIG. 7, the first column indicates the “Test #”, which refers to adistinct test that was performed on a specified material, in which thematerial was cut a number of times with both the “R&D Control” blade andthe “Chip Model” blade to determine how many cuts could be performed onthe material before each blade failed. The second column indicates thematerial being cut (i.e., the materials were of types “A”, “B”, “C” or“D”), the third column indicates the results (i.e, the number of cutsthat each blade performed before failing for each of the differentmaterials being cut) for the “R&D Control”, the fourth column indicatesthe results for the “Chip Model” or blade embodying the presentinvention (i.e., the number of cuts achieved prior to failure), and thefifth column illustrates the improved results provided by the blade ofthe present invention (i.e., a comparison of column 4 to column 3).

For each test, the blades were tested in groups of about 6 to 8 bladesper group. The number of cuts that each blade performed before failingwas averaged to produce the number of cuts listed for each test in FIG.7. A “cut” as defined in the context of FIGS. 7 and 8 refers to acomplete cutting through of a predetermined portion of the material witha reciprocating saw fitted with the blade to be tested. Failure wasdetermined by observing the amount of time, i.e., cutting time, requiredfor a blade to cut through the width of a material, or through thepredetermined portion of the material, and comparing the cutting time toa threshold cutting time. Factors including the type of material andamount of downforce applied to the blade were considered in calculatingthe threshold cutting time. When the time required to make a completecut of the material exceeded the threshold cutting time, the blade wasconsidered to have failed. In the present embodiment, an average cuttingtime for each cut was calculated by averaging the cutting time of eachof the last three cuts performed, i.e., the current cut and the twoimmediately previous cuts. When this average cutting time exceeded thethreshold cutting time, the blade was deemed to have failed. The numberof cuts listed in FIG. 7 is the average number of cuts that a group ofeither the “R&D Control” or “Chip Model” blades was able to performbefore the average cutting time exceeded the threshold cutting time(i.e., failure).

For example, for the case of a blade applied via a reciprocating saw toa 1-inch diameter black pipe, shown as material C in FIG. 7, with about25 pounds of downforce, the threshold cutting time was determined to be45 seconds. A blade that would take longer than 45 seconds to cutthrough the material in this test was considered to have failed. Eachblade was applied to the material to perform numerous cuts in thematerial. The cutting time of each cut was observed, and the averagecutting time of the latest three cuts was continuously calculated. Asmore and more cuts were made, the blade would wear down, and each cutwould take longer to complete. Once the average cutting time exceededthe threshold cutting time, the blade was deemed to have failed. Thenumber of cuts made in the material prior to this failure was recordedas a measure of the durability of the blade. The number of cuts recordedfor each blade in the group was averaged to determine the number of cutsshown in FIG. 7.

As can be seen, for example, in the test labeled RC674, the “Chip Model”blade was able to make an average of 53.5 cuts before failing, whereasthe “R&D Control” blade was only able to make an average of 22.9 cutsbefore failing. The “Chip Model” blade thus exhibited about 133% greaterdurability than the “R&D Control” blade. As shown in the table of FIG.7, the “Chip Model” embodiment of the present invention was generallymuch more durable, i.e., performed significantly more cuts beforefailing, than the prior art “R&D Control” blade.

FIG. 8 shows additional test results of the “Chip Model” embodimentcompared to a “R&D Control” blade. The “R&D Control” and “Chip Model”blades of FIG. 8 are similar to those of FIG. 7. FIG. 8 also shows testresults of an embodiment of a reciprocating saw blade having a cuttingangle with respect to the reciprocating motion of the reciprocating saw.This reciprocating saw blade having a cutting angle is labeled “6° TangChip Model”. This “6° Tang Chip Model” embodiment is similar to the“Chip Model”, but also includes a tang angle of about 6°, which in turndefines a cutting angle of about 6°. Both the “6° Tang Chip Model” andthe “Chip Model” blades were tested against a typical “R&D Control” sawblade that did not have the height differential or clearance anglefeatures of the “Chip Model” embodiment, or the tang and cutting anglefeatures of the “6° Tang Chip Model” embodiment. The table of FIG. 8shows the number of cuts that each blade performed on a respectivematerial before failing.

In FIG. 8, the first column indicates the “Test #”, which refers to thetest that was performed on a specified material, in which the materialwas cut a number of times with the “R&D Control” blade, the “Chip Model”blade, and the “6° Tang Chip Model” blade to determine how many cutscould be performed on the material before each blade failed. The secondcolumn indicates the material being cut (i.e., the materials were oftypes “A”, “B”, “C”, “D”, “E” or “F”), the third column indicates forthe “R&D Control” blade the results (i.e., the number of cuts that eachblade performed before failing for each of the different materials beingcut), the fourth column indicates the results for the “Chip Model”blade, the fifth column indicates the results for the “6° Tang ChipModel” blade, and the sixth column illustrates the improved resultsprovided by the “6° Tang Chip Model” blade of the present inventionrelative to the “R&D Control” blade (i.e., a comparison of column 5 tocolumn 3).

The procedure for each test indicated in FIG. 8 is similar to each ofthe tests indicated in FIG. 7. In each case the blades were tested ingroups of about 6 to 8 blades per group. The number of cuts that eachblade performed before failing for each blade was averaged to producethe number of cuts listed for each test in FIG. 8. Failure wasdetermined by observing the cutting time required for a blade to cutthrough the width of a material, or through a predetermined portion ofthe material, and comparing the cutting time to the threshold cuttingtime. The number of cuts indicated in FIG. 8 is the average number ofcuts that a group of either the “R&D Control”, “Chip Model” or “6° TangChip Model” blade was able to perform before the average cutting timeexceeded the threshold cutting time (i.e., failure). As shown in thetable of FIG. 8, both the “6° Tang Chip Model” and “Chip Model”embodiments exhibited significantly improved durability, i.e., performedsignificantly more cuts before failing, than the prior art “R&D Control”blade.

FIGS. 9-12 show additional exemplary reciprocating saw blades embodyingthe present invention. The blade portion of each of these saw blades hasa repeating tooth pattern or group that includes at least one firstrelatively high unset tooth, a first plurality of set teeth followingthe first relatively high unset tooth and set to one side of the bladeportion, at least one second relatively high unset tooth following thefirst plurality of set teeth, and a second plurality of set teethfollowing the at least one second relatively high unset tooth and set toan opposite side of the blade portion relative to the first plurality ofset teeth. In some such embodiments, a plurality of at least one of thefirst and second pluralities of set teeth define different setmagnitudes and different heights relative to each other.

In FIG. 9, the reciprocating saw blade 700 is substantially similar tothe reciprocating saw blades described above in connection with FIGS.1-8, and therefore like reference numerals preceded by the numeral “7”instead of the numerals “1” through “6” are used to indicate likeelements. The recip blade 700 includes a ten-tooth pattern 705 thatincludes a high unset tooth 710 followed by a first plurality 707 ofleft set teeth, a second high unset tooth 710 following first plurality707, and a second plurality 709 of right set teeth following the secondhigh unset tooth 710. Alternatively, first plurality 707 may be rightset, and second plurality 709 may be left set. At least one of firstplurality 707 and second plurality 709 includes at least oneintermediate height set tooth 717L and/or 717R that is relatively lightset, and at least one low set tooth 715L and/or 715R that is relativelyheavy set.

More specifically, first plurality 707 includes two intermediate heightlight set teeth 717L and two low heavy set teeth 715L, which are all setto the left of the blade portion of blade 700, and second plurality 709includes intermediate height light set teeth 717R and two low heavy setteeth 715R, which are all set to the right of the blade portion. Highunset teeth 710 have a first height 730, low set teeth 715L, 715R have asecond height 735, and intermediate height light set teeth 717L, 717Rhave a third height 732. First height 730 is greater than third height732, and third height 732 is greater than second height 735. In oneembodiment, the difference in height between each intermediate heightlight set tooth 717L, 717R prior to tooth set and a respective precedingunset tooth 710 is at least about 0.002 inch, and the difference inheight between each intermediate height set tooth and low set toothprior to tooth set is at least about 0.002 inch. As may be recognized bythose of ordinary skill in the pertinent art based on the teachingsherein, numerous other height differentials equally may be employed.Intermediate height light set teeth 717L, 717R may be set to a first setmagnitude, and low set teeth 715R and 715L may be set to a secondmagnitude greater than the first set magnitude.

The set teeth may be positioned to so that the magnitude of one or moreof the height and set of each tooth in the pluralities 707 and 709 formsa wavy height and/or set design. In this embodiment, the magnitude ofthe tooth heights progressively decreases and the magnitude of the toothsets progressively increases, and then the magnitude of the toothheights progressively increases and the magnitude of the tooth setsprogressively decreases, along a curve. As a result, the progression ofheight and/or set magnitude along the elongated axis of the cuttingportion of the blade 700 forms a wave-like pattern. For example, asshown in FIG. 9, the five-tooth progression of plurality 707 includesunset high tooth 710, followed successively by a first intermediateheight light set tooth 717L, two low heavy set teeth 715L, and a secondintermediate light set tooth 717L. Plurality 709 exhibits a similarpattern of unset high tooth 710 and corresponding right set teeth.

In one embodiment, unset high tooth 710 has a clearance angle that isrelatively small compared to the clearance angles of the intermediatelight set teeth 717L, 717R and the low heavy set teeth 715L, 715R.Intermediate light set teeth 717L, 717R may each have a clearance anglethat is substantially the same as the clearance angles of low set teeth715L, 715R, or the clearance angles of the set teeth may differ fromeach other. For example, the intermediate height light set teeth maydefine a more shallow clearance angle than the low heavy set teeth, butsteeper clearance angles then the high unset teeth. Alternatively, allof the teeth in pattern 705 may have approximately the same clearanceangle. In one example, intermediate light set teeth 717L, 717R and lowheavy set teeth 715L, 715R each have a clearance angle of about 40°, andhigh unset teeth 710 each have a clearance angle of about 30°.

In FIG. 10, another reciprocating saw blade embodying the presentinvention is indicated generally by the reference numeral 800. Thereciprocating saw blade 800 is substantially similar to thereciprocating saw blades described above in connection with FIGS. 1-9,and therefore like reference numerals preceded by the numeral “8”instead of the numerals “1” through “7” are used to indicate likeelements.

The recip blade 800 includes an eight-tooth pattern 805 that includes ahigh unset tooth 810 followed by a first plurality 807 of left setteeth, a second high unset tooth 810 following first plurality 807, anda second plurality 809 of right set teeth following the second highunset tooth 810. Alternatively, first plurality 807 may be right setteeth, and second plurality 809 may be left set teeth. At least one offirst plurality 807 and second plurality 809 includes at least oneintermediate height tooth 817L and/or 817R that is relatively light set,and at least one low tooth 815L and/or 815R that is relatively heavyset.

More specifically, first plurality 807 includes intermediate light setteeth 817L and low heavy set tooth 815L, which are all set to the leftof the blade portion of blade 800, and second plurality 809 includesintermediate light set teeth 817R and low heavy set tooth 815R, whichare all set to the right of the blade portion. High unset teeth 810 havea first height 830, low heavy set teeth 815L, 815R have a second height835, and intermediate light set teeth 817L, 817R have a third height832. First height 830 is greater than third height 832, and third height832 is greater than second height 835. In one embodiment, the differencein height between each intermediate height light set tooth 817L, 817Rprior to tooth set and a respective preceding unset tooth 810 is atleast about 0.002 inch, and the difference in height between eachintermediate height light set tooth and low heavy set tooth prior totooth set is at least about 0.002 inch.

Similar to the tooth pattern 705 of FIG. 9, the set teeth of toothpattern 805 may be positioned so that one or more of the magnitude ofthe height and set of each tooth in the pluralities 807 and 809progresses successively along a curve to form a wave pattern. Forexample, as shown in FIG. 10, the four-tooth progression of plurality807 includes unset high tooth 810, followed successively by a firstintermediate height light set tooth 817L, low heavy set tooth 815L, anda second intermediate height light set tooth 817L. Plurality 809exhibits a similar pattern of unset high tooth 810 and correspondingright set teeth.

In one embodiment, unset high tooth 810 has a clearance angle that isrelatively small compared to the clearance angles of intermediate heightlight set teeth 817L, 817R and low heavy set teeth 815L, 815R.Intermediate height teeth 817L, 817R may each have a clearance anglethat is substantially the same as the clearance angles of low heavy setteeth 815L and 815R, or the clearance angles of the set teeth may bevariable. Alternatively, all of the teeth in tooth pattern 805 may haveapproximately the same clearance angle. In one example, intermediateheight light set teeth 817L, 817R and low heavy set teeth 815L, 815Reach have a clearance angle of about 40°, and high unset teeth 810 eachhave a clearance angle of about 30°.

In FIG. 11, another reciprocating saw blade embodying the presentinvention is indicated generally by the reference numeral 900. Thereciprocating saw blade 900 is substantially similar to thereciprocating saw blades described above in connection with FIGS. 1-10,and therefore like reference numerals preceded by the numeral “9”instead of the numerals “1” through “8” are used to indicate likeelements.

The reciprocating blade 900 includes a ten-tooth pattern 905 thatincludes a high unset tooth 910 followed by a first plurality 907 ofleft set teeth, a second high unset tooth 910 following first plurality907, and a second plurality 909 of right set teeth following the secondhigh unset tooth 910. At least one of the first plurality 907 and secondplurality 909 includes at least one high relatively light set tooth, andat least one low relatively heavy set tooth. The at least one highrelatively light set tooth defines a height prior to tooth set that isapproximately equal to or less than the height of the preceding unsettooth 910.

More specifically, first plurality 907 includes high light set teeth920L and low heavy set teeth 915L, which are all set to the left of theblade portion of blade 900, and the second plurality 909 includes highlight set teeth 920R and low heavy set teeth 915R, which are all set tothe right of the blade portion. The high unset teeth 910 have a firstheight 930, low heavy set teeth 915L, 915R have a second height 935 thatis lower than first height 930, and high light set teeth 920L, 920R havea height that is approximately equal to height 930 prior to tooth set.High light set teeth 920L, 920R may be set to a first set magnitude, andlow heavy set teeth 915R, 915L may be set to a second magnitude greaterthan the first set magnitude.

In one embodiment, high unset tooth 910 has a clearance angle that isrelatively small compared to the clearance angles of low heavy set teeth915L, 915R. High light set teeth 920L, 920R may have a clearance anglethat is substantially equal to the clearance angle of high unset tooth910. The clearance angle of high light set teeth 920L, 920Ralternatively may be greater than the clearance angle of high unsettooth 910. High light set teeth 920L, 920R each may have a clearanceangle that is substantially the same as the clearance angles of lowheavy set teeth 915L, 915R, or the clearance angles of the set teeth maybe variable. Alternatively, all of the teeth in tooth pattern 905 mayhave approximately the same clearance angle. In one example, low heavyset teeth 915L, 915R each have a clearance angle of about 40°, and highunset teeth 910 and high light set teeth 920L, 920R each have aclearance angle of about 30°.

Similar to the embodiments shown in FIGS. 9 and 10, low heavy set teeth915L, 915R are positioned in between high light set teeth 920L, 920Rrespectively, so that the magnitude of the height and/or set of theteeth progresses along the blade portion in a wave-like pattern. Forexample, as shown in FIG. 11, the five-tooth progression of plurality907 includes high unset tooth 910, followed successively by a first highlight set tooth 920L, two low heavy set teeth 915L, and a second highlight set tooth 920L. Plurality 909 exhibits a similar pattern of unsethigh tooth 910 and corresponding right set teeth.

In FIG. 12, a reciprocating saw blade embodying the present invention isindicated generally by the reference numeral 1000. The reciprocating sawblade 1000 is substantially similar to the reciprocating saw bladesdescribed above in connection with FIGS. 1-11, and therefore likereference numerals preceded by the numeral “10” instead of the numerals“1” through “9” are used to indicate like elements.

The recip blade 1000 includes a six-tooth pattern 1005 that includes ahigh unset tooth 1010 followed by a first plurality 1007 of left setteeth, a second high unset tooth 1010 following first plurality 1007,and a second plurality 1009 of right set teeth following the second highunset tooth 1010. At least one of the first plurality 1007 and thesecond plurality 1009 include at least one low set tooth. The at leastone low set tooth defines a height that is approximately equal to orless than the height of the preceding unset tooth 1010. As can be seen,tooth pattern 1005 is similar to tooth pattern 905 shown in FIG. 11,with the exception that tooth pattern 1005 does not include additionalset teeth that are higher than the low set teeth.

More specifically, first plurality 1007 includes set teeth 1015L, whichare all set to the left of the blade portion of the blade 1000, andsecond plurality 1009 includes set teeth 1015R, which are all set to theright of the blade portion. High unset teeth 1010 have a first height1030, and low set teeth 1015L, 1015R have a second height 1035 that islower than first height 1030. In this embodiment, unset high tooth 1010has a clearance angle that is relatively small compared to the clearanceangles of low set teeth 1015L, 1015R. In one example, low set teeth1015L, 1015R each have a clearance angle of about 40°, and high unsetteeth 1010 each have a clearance angle of about 30°. Alternatively, allof the teeth in tooth pattern 1005 may have approximately the sameclearance angle. The three-tooth progression of plurality 1007 includesunset high tooth 1010 followed successively by low heavy set teeth1015L. Plurality 1009 exhibits a similar pattern of unset high tooth1010 and corresponding right set teeth. If desired, the set magnitudesmay vary to form a more wave-like pattern.

Turning to FIG. 13, another reciprocating saw blade embodying thepresent invention is indicated generally by the reference numeral 1100.The reciprocating saw blade 1100 is substantially similar to thereciprocating saw blades described above in connection with FIGS. 1-12,and therefore like reference numerals preceded by the numeral “11”instead of the numerals “1” through “10” are used to indicate likeelements. A primary difference of the recip saw blade 1100 in comparisonto the recip saw blades described above is that the recip saw blade 1100defines a variable pitch pattern. More specifically, the recip saw blade1100 defines a variable-pitch, three tooth set pattern, including afirst relatively high unset tooth 1110, followed by a low left settrailing tooth 1115L and a low right set trailing tooth 1115R. The ΔHbetween the high and low teeth prior to tooth set is at least about0.002 inch, and in the illustrated embodiment is about 0.005 inch. Thefirst clearance angle A of the high teeth is less than the secondclearance angle B of the low teeth. In the illustrated embodiment, thefirst clearance angle A of the high teeth is about 30°, and the secondclearance angle B of the low teeth is about 40°. As with the tooth formsdescribed above, each tooth 1110, 1115 defines a primary clearancesurface forming either the first or second clearance angle A or B, and asecondary clearance surface forming the third clearance angle C. Asindicated above, each third clearance angle C is preferably greater thanthe respective primary clearance angle A or B. In the illustratedembodiment, the first clearance angle A is about 30°, the secondclearance angle B is about 40°, and the third clearance angle C is about45°. As can be seen, the first pitch P1 of each unset tooth 1110 is arelatively coarse pitch, and the second pitch P2 of the trailing teeth1115L, 1115R is a relatively fine pitch. In the illustrated embodiment,the first pitch P1 is a 10 pitch, the second pitch P2 is a 14 pitch, andthus the recip blade 1100 defines a 10/14 repeating pitch pattern. Asmay be recognized by those of ordinary skill in the pertinent art basedon the teachings herein, these particular height differentials,clearance angles, and pitches are only exemplary, and any of numerousdifferent height differentials, clearance angles, pitches, and/or pitchpatterns, and/or any of numerous different variable pitch patterns, thatare currently known, or that later become known, equally may beemployed. For example, a finer pitch pattern, such as a 14/18 pitchpattern may employ a lesser ΔH than described above in connection withFIG. 13, such as a ΔH of about 0.003 inch.

One of the drawbacks of prior art variable pitch recip blades is thatthe unset teeth, or the teeth with the largest pitch and/or gullets,define relatively weak points on the blade and tend to prematurely fail.A significant advantage of some currently preferred embodiments of thevariable pitch recip blades of the present invention is that the teethwith the largest gullets are the unset raker teeth having a relativelyhigh tooth height and shallow clearance angle, and thus a relativelyrobust tooth form in comparison to the other teeth of the saw blade. Asa result, such embodiments of the variable pitch recip blades of thepresent invention can provide significantly improved durability and/orblade life in comparison to prior art variable pitch recip blades.However, the high unset raker of the recip blades of the presentinvention need not define the largest pitch or gullet. Other variablepitch recip blade embodiments of the present invention define variablepitch embodiments having unset raker teeth define smaller, or at leastnot the largest gullets. For example, another recip blade embodiment ofthe present invention defines a repeating 3-tooth set pattern and avariable pitch pattern including a high unset leading tooth followed bya low right set trailing tooth and a low left set trailing tooth. Inthis embodiment, the low left set trailing tooth defines the coarsepitch P1, and the high unset tooth and low right set trailing tooth eachdefine the finer pitch P2. Otherwise, the teeth define the same heightdifferentials and clearance angles as the corresponding teeth of therecip blade 1100 of FIG. 13. These recip blades are also capable ofproviding significant advantages with respect to cutting speed anddurability for the reasons summarized above.

Turning to FIG. 14, another reciprocating saw blade embodying thepresent invention is indicated generally by the reference numeral 1200.The reciprocating saw blade 1200 is substantially similar to thereciprocating saw blades described above in connection with FIG. 13, andtherefore like reference numerals preceded by the numeral “12” insteadof the numeral “11” are used to indicate like elements. A primarydifference of the recip blade 1200 in comparison to the recip blade 1100described above is that it defines a 6-tooth set pattern with a 3-toothvariable pitch pattern. As can be seen, the 6-tooth set pattern isdefined by a first high unset leading tooth 1210 followed by two lowleft set trailing teeth 1215, and a second high unset leading tooth 1210followed by two low right set trailing teeth 1215. As can be seen, therecip saw blade 1200 defines a wave-like set pattern. Otherwise, therecip saw blade 1200 defines the same ΔH, clearance angles, and pitches(i.e., a 10/14 repeating pitch pattern) as the recip saw blade 1100described above in connection with FIG. 13.

In FIG. 15, another reciprocating saw blade embodying the presentinvention is indicated generally by the reference numeral 1300. Thereciprocating saw blade 1300 is substantially similar to thereciprocating saw blades described above in connection with FIGS. 1-13,and therefore like reference numerals preceded by the numeral “13”, orpreceded by the numeral “13” instead of another lead numeral, are usedto indicate like elements. A primary difference of the recip blade 1300in comparison to the recip blades described above, is that the recipblade 1300 defines a variable height, variable clearance and variableset magnitude. More specifically, each repeating tooth pattern of therecip blade 1300 includes a relatively high raker or unset tooth 1310,followed by a relatively low, heavy right set tooth 1315R, a relativelyhigh, light left set tooth 1320L, a relatively high, light right settooth 1320R, and a relatively low, heavy left set tooth 1315L. In theillustrated embodiment, the height differential ΔH between therelatively high teeth 1310, 1320L, 1320R and the relatively low teeth1315R and 1315L prior to tooth set is about 0.004 inch, the firstprimary clearance angle A is about 30°, the second primary clearanceangle B is about 40°, and the secondary clearance angle C is about 42°for the relatively high teeth 1310, 1320 and about 45° for therelatively low teeth 1315, and the pitch is about 14 TPI. As may berecognized by those of ordinary skill in the pertinent art based on theteachings herein, this height differential, the clearance angles, theset magnitudes, and the pitch are only exemplary, and numerous otherheight differentials, clearance angles, set magnitudes, and pitches,including variable pitches, that are currently known, or that laterbecome known, equally may be employed. In addition, any of numerousdifferent teeth may define the heavy sets and any of numerous otherteeth may define the light sets. For example, a light set tooth mayimmediately follow each heavy set tooth and vice versa. It has beendetermined with respect to some embodiments of the present inventionthat the variable set magnitudes provide improved performance withrespect to cutting speed and/or durability. For example, in some suchembodiments the relatively low teeth are heavy set, and the relativelyhigh set teeth are light set, and in some such embodiments, therelatively low teeth define steeper clearance angles and the relativelyhigh teeth define more shallow clearance angles.

As may be recognized by those of ordinary skill in the pertinent artbased on the teachings herein, any of these variables may be changed asdesired or otherwise required, and/or any of numerous different variablepitch patterns, that are currently known, or that later become known,equally may be employed. For example, another variable pitch recip bladeof the present invention defines a 6-tooth set pattern having arepeating 3-tooth variable pitch pattern including a high unset leadingtooth followed by two low right set trailing teeth, and another highunset leading tooth following by two low left set trailing teeth. Inthis embodiment, the set tooth and the first trailing tooth define thefiner pitches P2, and each second trailing tooth defines the coarserpitch P1. Otherwise, the teeth define the same height differentials andclearance angles as the corresponding teeth of the recip blade 1200 ofFIG. 14. Another variable pitch recip blade of the present inventiondefines a three-tooth set pattern with a six-tooth variable pitchpattern. In this embodiment, the repeating three-tooth set patternconsists of an unset leading tooth following by opposite set trailingteeth (i.e., a left set trailing tooth followed by a right set trailingtooth, or vice versa); and the six-tooth variable pitch pattern consistsof a first three-tooth set pattern wherein each tooth defines arelatively coarse pitch (e.g., a 10 pitch), and a second three-toothpattern wherein each tooth defines a relatively fine pitch (e.g., a 14pitch). In one such embodiment, the unset teeth define relatively highteeth with more shallow clearance angles, and the trailing set teethdefine relatively low teeth with steeper clearance angles.

As may be recognized by those of ordinary skill in the pertinent artbased on the teachings herein, numerous changes and modifications can bemade to the above-described and other embodiments of the presentinvention without departing from the scope of the invention as definedin the appended claims. For example, in some embodiments the teeth arecarbide tipped; however, the teeth also may define any of numerousdifferent constructions that are currently known, or that later becomeknown, including bi-metal or other constructions. Further, the sawblades of the present invention may be coated with any of numerousdifferent coatings that are currently known or that later become known,such as a titanium nitride coating (TiN), aluminum titanium nitride(AlTiN), or combinations thereof, or the saw blades may not include anycoating at all. Numerous other features of the saw blades disclosedherein may be changed as desired, or otherwise as required to meet therequirements of a particular application. Accordingly, this detaileddescription of the currently preferred embodiments is to be taken in anillustrative, as opposed to a limiting sense.

1. A reciprocating saw blade for use in a portable power reciprocatingsaw including a chuck for releasably engaging the saw blade, thereciprocating saw blade comprising: a reciprocating saw blade tanghaving an elongated axis and being engageable with the chuck of thereciprocating saw for attaching the reciprocating saw blade to thereciprocating saw; and a reciprocating saw blade portion having acutting edge defined by a plurality of cutting teeth, wherein thecutting teeth define a repeating pattern of successive groups of teeth,each group of teeth includes a plurality of set teeth, at least onerelatively high tooth, and at least one relatively low tooth, andwherein prior to tooth set the at least one relatively high tooth is atleast about 0.002 inch higher than the at least one relatively lowtooth.
 2. A reciprocating saw blade as defined in claim 1, wherein priorto tooth set the difference in height between the at least onerelatively high tooth and the at least one relatively low tooth iswithin the range of about 0.003 inch to about 0.006 inch. 3-5.(canceled)
 6. A reciprocating saw blade as defined in claim 1, whereineach group of teeth is less than about a half inch in length, andincludes at least one unset leading tooth, and a plurality of settrailing teeth.
 7. A reciprocating saw blade as defined in claim 6,wherein the at least one unset leading tooth is a relatively high tooth,and at least one of the plurality of set trailing teeth is a relativelylow tooth.
 8. A reciprocating saw blade as defined in claim 7, whereinat least one of the set trailing teeth is a relatively high tooth.
 9. Areciprocating saw blade as defined in claim 1, wherein a plurality ofthe set trailing teeth define different set magnitudes relative to eachother.
 10. A reciprocating saw blade as defined in claim 9, wherein theplurality of set trailing teeth includes at least one first set toothdefining a relatively heavy set magnitude, and at least one second settooth defining a relatively light set magnitude.
 11. A reciprocating sawblade as defined in claim 10, wherein the at least one first set toothdefining a heavy set magnitude is a relatively low tooth, and the atleast one second set tooth defining a relatively light set magnitude ishigher than the heavy set tooth.
 12. A reciprocating saw blade asdefined in claim 11, wherein the at least one relatively low heavy settooth defines a steeper clearance angle in comparison to the at leastone relatively high light set tooth.
 13. A reciprocating saw blade asdefined in claim 1, wherein each group of teeth includes unset teethbetween first and second pluralities of set teeth.
 14. A reciprocatingsaw blade as defined in claim 13, wherein each of the first and secondpluralities of set teeth includes at least one relatively high settooth, and at least one relatively low set tooth.
 15. A reciprocatingsaw blade as defined in claim 14, wherein the unset teeth define atleast one first clearance angle, the set teeth define at least onesecond clearance angle, and the at least one first clearance angle isless than the at least one second clearance angle.
 16. A reciprocatingsaw blade as defined in claim 1, wherein the reciprocating saw causesthe saw blade to move in a reciprocating motion between a rear mostposition and a forward most position, the reciprocating motion definesan axis of motion extending between i) a first position of a referencepoint of the saw blade when the saw blade is in the rear most positionand ii) a second position of the reference point when the saw blade isin the forward most position, the cutting edge defines an approximatecutting line extending between tips of successive teeth havingsubstantially the same height, and the cutting line is oriented at anacute angle of greater than about 3° relative to the axis of motion. 17.A reciprocating saw blade as defined in claim 16, wherein the acuteangle is within the range of about 4½° to about 6°.
 18. A reciprocatingsaw blade as defined in claim 16, wherein the tang defines an elongatedaxis oriented at an acute tang angle relative to the cutting line whichat least contributes to orienting the cutting line at an acute angle ofgreater than about 3° relative to the axis of motion.
 19. Areciprocating saw blade as defined in claim 16, wherein the relativelyhigh teeth define at least one first clearance angle within the range ofabout 25° to about 35°, the relatively low teeth define at least onesecond clearance angle within the range of about 35° to about 45°, theacute angle is greater than about 3° and less than or equal to about 6°,and the difference in height between the at least one relatively hightooth and the at least one relatively low tooth is at least about 0.003inch.
 20. A reciprocating saw blade as defined in claim 1, wherein eachgroup includes at least one first relatively high unset tooth, a firstplurality of set teeth following the first relatively high unset toothand set to one side of the blade portion, at least one second relativelyhigh unset tooth following the first plurality of set teeth, and asecond plurality of set teeth following the at least one secondrelatively high unset tooth and set to an opposite side of the bladeportion relative to the first plurality of set teeth.
 21. Areciprocating saw blade as defined in claim 20, wherein a plurality ofat least one of the first and second pluralities of set teeth definedifferent set magnitudes and different heights relative to each other.22. A reciprocating saw blade as defined in claim 21, wherein at leastone of the first and second pluralities of set teeth includes at leastone intermediate height tooth that is relatively light set, and at leastone low tooth that is relatively heavy set, wherein the intermediateheight tooth defines a height between the heights of the relatively highand low teeth, and the difference in height between each intermediateheight tooth and adjacent high and low teeth prior to tooth set is atleast about 0.002 inch.
 23. A reciprocating saw blade as defined inclaim 1, wherein each group of teeth defines a variable pitch pattern,including at least one relatively coarse pitch and at least onerelatively fine pitch.
 24. A reciprocating saw blade as defined in claim23, wherein each group of teeth includes an unset raker tooth defining arelatively coarse pitch.
 25. A reciprocating saw blade as defined inclaim 1, wherein each group of teeth includes a plurality of low teeth,and each low tooth includes a rake face defining a positive rake angle.26. A reciprocating saw blade for use in a portable power reciprocatingsaw, the reciprocating saw blade comprising: first means engageable withthe reciprocating saw for attaching the reciprocating saw blade to thereciprocating saw; and a reciprocating saw blade cutting edge defined bya plurality of second means for cutting, wherein the second means definea repeating pattern of successive groups thereof, each group includes aplurality of second means laterally set to opposite sides of the cuttingedge relative to each other, at least one relatively high second means,and at least one relatively low second means, and wherein prior to beinglaterally set the at least one relatively high second means is at leastabout 0.002 inch higher than the at least one relatively low secondmeans.
 27. A reciprocating saw as defined in claim 26, wherein the firstmeans is a tang and each second means is a tooth.
 28. A reciprocatingsaw as defined in claim 27, wherein each group of teeth is less thanabout a half inch in length, and wherein the reciprocating saw causesthe reciprocating saw blade to move in a reciprocating motion between arear most position and a forward most position, the motion defines anaxis of motion extending between i) a first position of a referencepoint of the saw blade when the saw blade is in the rear most positionand ii) a second position of the reference point when the saw blade isin the forward most position, the cutting edge defines an approximatecutting line extending between successive second means havingsubstantially the same height, and the reciprocating saw blade furtherincludes means for orienting the cutting line at an acute angle ofgreater than about 3° relative to the axis of motion.
 29. A methodcomprising the following steps: mounting within a chuck of areciprocating saw a reciprocating saw blade including a tang having anelongated axis and a blade portion having a cutting edge defined by aplurality of cutting teeth; wherein the cutting teeth define a repeatingpattern of successive groups of teeth, each group of teeth includes aplurality of teeth of different species, including a plurality of setteeth, at least one relatively high tooth, and at least one relativelylow tooth; and wherein prior to tooth set the at least one relativelyhigh tooth is at least about 0.002 inch higher than the at least onerelatively low tooth; driving the reciprocating saw blade with thereciprocating saw in a reciprocating cutting action between forward andbackward strokes; and cutting a work piece by engaging the work piecewith the reciprocatingly driven reciprocating saw blade and, in turn,during each of a plurality of forward strokes, engaging multiple teethof the same species with the work piece, bearing a relatively higherchip load with the relatively high teeth in comparison to the relativelylow teeth, protecting the relatively low teeth from chipping or damagewith the preceding relatively high teeth, and cutting the work piecewith the relatively low teeth at a higher speed in comparison to therelatively high teeth.
 30. A method as defined in claim 29, wherein eachgroup of teeth is less than about a half inch in length, and wherein thestep of driving the reciprocating saw blade comprises driving thereciprocating saw blade in a reciprocating motion between a rear mostposition and a forward most position, wherein the reciprocating motiondefines an axis of motion extending between i) a first position of areference point of the saw blade when the saw blade is in the rear mostposition, and ii) a second position of the reference point when the sawblade is in the forward most position, and the cutting edge defines anapproximate cutting line extending between tips of successive teethhaving substantially the same height, and further comprising the step ofpositioning or orienting the cutting line at an acute angle of greaterthan about 3° relative to the axis of motion
 31. A method as defined inclaim 30, wherein the step of positioning or orienting the cutting lineat an acute angle includes at least one of: (i) providing the tang sothat the elongated axis of the tang defines an acute angle relative tothe cutting line, and (ii) mounting the tang within the chuck so thatthe cutting line is oriented at an acute angle relative to the axis ofmotion.
 32. A reciprocating saw blade as defined in claim 1, wherein therelatively high teeth define at least one first clearance angle, and therelatively low teeth define at least one corresponding second clearanceangle substantially the same as the first clearance angle, whereineither (i) the at least one first clearance angle defines a primaryclearance angle of the relatively high teeth and the at least one secondclearance angle defines a primary clearance angle of the relatively lowteeth; or (ii) the at least one first clearance angle defines asecondary clearance angle of the relatively high teeth and the at leastone second clearance angle defines a secondary clearance angle of therelatively low teeth.
 33. A reciprocating saw blade as defined in claim32, wherein the at least one first clearance angle defines a primaryclearance angle of the relatively high teeth and the at least one secondclearance angle defines a primary clearance angle of the relatively lowteeth.
 34. A reciprocating saw blade as defined in claim 32, wherein theat least one first clearance angle defines a secondary clearance angleof the relatively high teeth and the at least one second clearance angledefines a secondary clearance angle of the relatively low teeth.
 35. Areciprocating saw blade as defined in claim 26, wherein the relativelyhigh second means defines at least one first clearance angle, and therelatively low second means defines at least one corresponding secondclearance angle substantially the same as the first clearance angle,wherein either (i) the at least one first clearance angle defines aprimary clearance angle of the relatively high second means and the atleast one second clearance angle defines a primary clearance angle ofthe relatively low second means; or (ii) the at least one firstclearance angle defines a secondary clearance angle of the relativelyhigh second means and the at least one second clearance angle defines asecondary clearance angle of the relatively low second means.
 36. Areciprocating saw blade as defined in claim 35, wherein the at least onefirst clearance angle defines a primary clearance angle of therelatively high second means and the at least one second clearance angledefines a primary clearance angle of the relatively low second means.37. A reciprocating saw blade as defined in claim 35, wherein the atleast one first clearance angle defines a secondary clearance angle ofthe relatively high second means and the at least one second clearanceangle defines a secondary clearance angle of the relatively low secondmeans.
 38. A method as defined in claim 29, wherein the relatively highteeth define at least one first clearance angle, and the relatively lowteeth define at least one corresponding second clearance anglesubstantially the same as the first clearance angle, wherein either (i)the at least one first clearance angle defines a primary clearance angleof the relatively high teeth and the at least one second clearance angledefines a primary clearance angle of the relatively low teeth; or (ii)the at least one first clearance angle defines a secondary clearanceangle of the relatively high teeth and the at least one second clearanceangle defines a secondary clearance angle of the relatively low teeth.39. A reciprocating saw blade as defined in claim 38, wherein the atleast one first clearance angle defines a primary clearance angle of theat least one relatively high tooth and the at least one second clearanceangle defines a primary clearance angle of the at least one relativelylow tooth.
 40. A reciprocating saw blade as defined in claim 38, whereinthe at least one first clearance angle defines a secondary clearanceangle of the at least one relatively high tooth and the at least onesecond clearance angle defines a secondary clearance angle of the atleast one relatively low tooth.
 41. A reciprocating saw blade for use ina portable power reciprocating saw including a chuck for releasablyengaging the saw blade, the reciprocating saw blade comprising: areciprocating saw blade tang having an elongated axis and beingengageable with the chuck of the reciprocating saw for attaching thereciprocating saw blade to the reciprocating saw; and a reciprocatingsaw blade portion having a cutting edge defined by a plurality ofcutting teeth including at least one relatively high tooth, and at leastone relatively low tooth, and wherein prior to any tooth set adifference in height between the at least one relatively high tooth andthe at least one relatively low tooth is at least about 0.002 inch;wherein the at least one relatively high tooth defines a first clearanceangle, and the at least one relatively low tooth defines a correspondingsecond clearance angle that is greater than the first clearance angle,wherein either (i) the first clearance angle defines a primary clearanceangle of the at least one relatively high tooth and the second clearanceangle defines a primary clearance angle of the at least one relativelylow tooth; or (ii) the first clearance angle defines a secondaryclearance angle of the at least one relatively high tooth and secondclearance angle defines a secondary clearance angle of the at least onerelatively low tooth.
 42. A reciprocating saw blade as defined in claim41, wherein the difference in height is within the range of about 0.003inch to about 0.006 inch.
 43. A reciprocating saw blade as defined inclaim 41, wherein the first clearance angle is less than or equal toabout 35°, and the second clearance angle is greater than about 35°. 44.A reciprocating saw blade as defined in claim 43, wherein the firstclearance angle is within the range of about 25° to about 35°, and thesecond clearance angle is within the range of about 35° to about 45°.45. A reciprocating saw blade as defined in claim 41, wherein theplurality of cutting teeth includes at least one unset tooth.
 46. Areciprocating saw blade as defined in claim 45, wherein the at least oneunset tooth is a relatively high tooth.
 47. A reciprocating saw blade asdefined in claim 41, wherein the plurality of cutting teeth includes atleast one set tooth.
 48. A reciprocating saw blade as defined in claim47, wherein the at least one set tooth is a relatively high tooth.
 49. Areciprocating saw blade as defined in claim 41, wherein thereciprocating saw causes the saw blade to move in a reciprocating motionbetween a rear most position and a forward most position, thereciprocating motion defines an axis of motion extending between i) afirst position of a reference point of the saw blade when the saw bladeis in the rear most position and ii) a second position of the referencepoint when the saw blade is in the forward most position, the cuttingedge defines an approximate cutting line extending between tips ofsuccessive teeth having substantially the same height, and the cuttingline is oriented at an acute angle of greater than about 3° relative tothe axis of motion.
 50. A reciprocating saw blade as defined in claim49, wherein the acute angle is within the range of about 4½° to about6°.
 51. A reciprocating saw blade as defined in claim 49, wherein thetang defines an elongated axis oriented at an acute tang angle relativeto the cutting line which at least contributes to orienting the cuttingline at an acute angle of greater than about 3° relative to the axis ofmotion.
 52. A reciprocating saw blade as defined in claim 49, whereinthe at least on e high tooth defines the first clearance angle withinthe range of about 25° to about 35°, the at least one relatively lowtooth defines the second clearance angle within the range of about 35°to about 45°, the acute angle is greater than about 3° and less than orequal to about 6°, and the difference in height is at least about 0.003inch.
 53. A reciprocating saw blade as defined in claim 41, wherein theplurality of cutting teeth defines a variable pitch pattern, includingat least one relatively coarse pitch and at least one relatively finepitch.
 54. A reciprocating saw blade as defined in claim 53, wherein theplurality of cutting teeth includes an unset raker tooth defining arelatively coarse pitch.
 55. A reciprocating saw blade as defined inclaim 41, wherein the plurality of cutting teeth includes a plurality oflow teeth, and each low tooth includes a rake face defining a positiverake angle.
 56. A reciprocating saw blade as defined in claim 41,wherein the first clearance angle defines a primary clearance angle ofthe at least one relatively high tooth and the second clearance angledefines a primary clearance angle of the at least one relatively lowtooth.
 57. A reciprocating saw blade as defined in claim 41, wherein thefirst clearance angle defines a secondary clearance angle of the atleast one relatively high tooth and the second clearance angle defines asecondary clearance angle of the at least one relatively low tooth. 58.A reciprocating saw blade for use in a portable power reciprocating saw,the reciprocating saw blade comprising: first means engageable with thereciprocating saw for attaching the reciprocating saw blade to thereciprocating saw; and a reciprocating saw blade cutting edge defined bya plurality of second means for cutting including at least onerelatively high second means, and at least one relatively low secondmeans, and wherein prior to any set a difference in height between theat least one relatively high second means and the at least onerelatively low means is at least about 0.002 inch; wherein the at leastone relatively high second means defines a first clearance angle, andthe at least one relatively low second means defines a correspondingsecond clearance angle that is greater than the first clearance angle,wherein either (i) the first clearance angle defines a primary clearanceangle of the at least one relatively high second means and the secondclearance angle defines a primary clearance angle of the at least onerelatively low second means; or (ii) the first clearance angle defines asecondary clearance angle of the at least one relatively high secondmeans and the second clearance angle defines a secondary clearance angleof the at least one relatively low second means.
 59. A reciprocating sawas defined in claim 58, wherein the first means is a tang and eachsecond means is a tooth.
 60. A reciprocating saw as defined in claim 59,wherein the reciprocating saw causes the reciprocating saw blade to movein a reciprocating motion between a rear most position and a forwardmost position, the motion defines an axis of motion extending between i)a first position of a reference point of the saw blade when the sawblade is in the rear most position and ii) a second position of thereference point when the saw blade is in the forward most position, thecutting edge defines an approximate cutting line extending betweensuccessive second means having substantially the same height, and thereciprocating saw blade further includes means for orienting the cuttingline at an acute angle of greater than about 3° relative to the axis ofmotion.
 61. A reciprocating saw blade as defined in claim 58, whereinthe first clearance angle defines a primary clearance angle of therelatively high second means and the second clearance angle defines aprimary clearance angle of the relatively low second means.
 62. Areciprocating saw blade as defined in claim 58, wherein the firstclearance angle defines a secondary clearance angle of the relativelyhigh second means and the second clearance angle defines a secondaryclearance angle of the relatively low second means.
 63. A methodcomprising the following steps: mounting within a chuck of areciprocating saw a reciprocating saw blade including a tang having anelongated axis and a blade portion having a cutting edge defined by aplurality of cutting teeth including at least one relatively high tooth,and at least one relatively low tooth; and wherein prior to any toothset a difference in height between the at least one relatively hightooth and the at least one relatively low tooth is at least about 0.002inch, wherein the at least one relatively high tooth defines a firstclearance angle, and the at least one relatively low tooth defines acorresponding second clearance angle that is greater than the firstclearance angle, wherein either (i) the first clearance angle defines aprimary clearance angle of the at least one relatively high tooth andthe second clearance angle defines a primary clearance angle of the atleast one relatively low tooth; or (ii) the first clearance angledefines a secondary clearance angle of the at least one relatively hightooth and the second clearance angle defines a secondary clearance angleof the at least one relatively low tooth; driving the reciprocating sawblade with the reciprocating saw in a reciprocating cutting actionbetween forward and backward strokes; and cutting a work piece byengaging the work piece with the reciprocatingly driven reciprocatingsaw blade and, in turn, during each of a plurality of forward strokes,engaging multiple teeth with the work piece, bearing a relatively higherchip load with the at least one relatively high tooth in comparison tothe at least one relatively low tooth, protecting the at least onerelatively low tooth from chipping or damage with the preceding at leastone relatively high tooth, and cutting the work piece with the at leastone relatively low tooth at a higher speed in comparison to the at leastone relatively high tooth.
 64. A method as defined in claim 63, whereinthe step of driving the reciprocating saw blade comprises driving thereciprocating saw blade in a reciprocating motion between a rear mostposition and a forward most position, wherein the reciprocating motiondefines an axis of motion extending between i) a first position of areference point of the saw blade when the saw blade is in the rear mostposition, and ii) a second position of the reference point when the sawblade is in the forward most position, and the cutting edge defines anapproximate cutting line extending between tips of successive teethhaving substantially the same height, and further comprising the step ofpositioning or orienting the cutting line at an acute angle of greaterthan about 3° relative to the axis of motion
 65. A method as defined inclaim 64, wherein the step of positioning or orienting the cutting lineat an acute angle includes at least one of: (i) providing the tang sothat the elongated axis of the tang defines an acute angle relative tothe cutting line, and (ii) mounting the tang within the chuck so thatthe cutting line is oriented at an acute angle relative to the axis ofmotion.
 66. A reciprocating saw blade as defined in claim 63, whereinthe first clearance angle defines a primary clearance angle of the atleast one relatively high tooth and the second clearance angle defines aprimary clearance angle of the at least one relatively low tooth.
 67. Areciprocating saw blade as defined in claim 63, wherein the firstclearance angle defines a secondary clearance angle of the at least onerelatively high tooth and the second clearance angle defines a secondaryclearance angle of the at least one relatively low tooth.